1. Field of the Invention
The present invention generally relates to a process for producing a thermoplastic resin composition, and a thermoplastic resin composition produced thereby. More specifically, this invention relates to technologies for the recycling of degraded thermoplastic resin comprising an alloy of a polycarbonate resin and an ABS resin.
2. Description of the Related Art
Recently, the trend towards recycling petrochemical products, and especially the recycling of plastics, has become apparent with the increase in concern about protection of the environment. Japanese Patent No. 3095739 describes a technique for recycling used plastics that is a thermal recovery method, which utilizes thermal energy generated from combustion.
Material recycling, which re-uses plastic as a raw starting material, is also known. However, material recycling may have the following concerns. Specifically, resin compositions can often degrade due to hydrolysis and exposure to UV light, so that properties such as their composition strength and flame retardancy will usually deteriorate. Therefore, even if a molded article collected from the marketplace is ground and then directly re-molded, it can often be difficult to obtain a molded article having strength and flame retardancy that is equivalent to that of a molded article obtained from a virgin resin. Thus, it can be difficult to use a re-molded article as a part of a product in the same field as that in which the molded article was used before collection. As a result, cascade recycling, in which such collected molded articles are used as a part of a product in a different field, has predominated.
Recently, there has been a trend to attempt to obtain recycled resin compositions having properties that are close to those of a virgin plastic of the same grade, by reproducing the properties inherent in the resin composition before recycling to form the post-recycled resin composition.
Japanese Patent Application Laid-Open No. 2004-352762 proposes a method for obtaining physical properties equivalent to those of a particular virgin plastic of the same grade. In this method, 3 to 10 wt % of a core-shell type graft rubbery elastomer and/or 0 to 2 wt % of fluoroolefin resin is/are incorporated into a recycled thermoplastic resin in which a polycarbonate resin and a styrenic resin, such as a high-impact polystyrene resin (HIPS), are mixed, at least one of which is collected plastic.
Alloy resins of polycarbonate and ABS (a copolymer of acrylonitrile, butadiene, and styrene) often have excellent properties in terms of strength and flame retardancy, and accordingly such plastics are used in a wide range of products, such as home appliances, information devices, communication devices and automobiles.
However, the product that is formed by grinding an alloy resin of polycarbonate and ABS still cannot be used to obtain a molded article having an impact strength and flame retardancy that are equivalent to that of the virgin resin after recycling.
Therefore, there remains a need for the establishment of a process for material recycling of a degraded thermoplastic resin containing an alloy resin of polycarbonate and ABS.